Habitat : Agaricus campestris is common in fields and grassy areas after rain from late summer onwards worldwide. It is often found on lawns in suburban areas. Appearing in small groups, in fairy rings, or solitary. Owing to the demise of horse drawn vehicles, and the subsequent decrease in the number of horses on pasture, the old ‘white outs’ of years gone by are becoming rare events. This species is rarely found in woodland.

Saprobic; growing alone, gregariously, or sometimes in fairy rings, in meadows, fields, lawns, and grassy areas; late fall to early winter (occasionally in summer; sometimes year-long in California); widely distributed and common in North America.

Description:
The meadow mushroom, Agaricus campestris, is a beautiful white mushroom that is closely related to the cultivated “button mushrooms” (Agaricus bisporus) sold in North American grocery stores. In most areas it is a fall mushroom and, as its common and Latin names suggest, it comes up in meadows, fields, and grassy areas, after rains. It is recognized by its habitat, its pink gills (covered up by a thin white membrane when the mushroom is young) which become chocolate brown as the mushroom matures, its quickly collapsing white ring, and the fact that it does not discolor yellow when bruised.

The North American forms of this mushroom are apparently numerous–and several closely related (identical?) species have been described, including Agaricus andrewii (cheilocystidia 11-18.5 µ wide; universal veil hyphae with inflated elements) and Agaricus solidipes (spores up to 12 µ long; cheilocystidia absent). See also Agaricus porphyrocephalus.

Edibil Uses:
It is widely collected and eaten, even by those who would not normally eat wild mushrooms. This mushroom is not commercially cultivated on account of its fast maturing and short shelf-life. Culinary uses of the meadow mushroom include eating it sauteed or fried, in sauces, or even sliced raw and included in salads. In flavor and texture, this mushroom is almost identical to the white button mushroom available in grocery stores in the United States. Be sure to rinse well to dislodge any sand, and also watch out for small, white larvae which tunnel through the stems and caps. Among the similar species mentioned above, there have been cases where the deadly toxic destroying angel (Amanita bisporigera) has been consumed by individuals who mistook it for this species. The edibility of specimens collected from lawns is uncertain because of possible contamination with pesticides or other chemicals.

Bioactive properties
Water extracts of A. campestris have been shown to enhance the secretion of insulin, and to have insulin-like effects on glucose metabolism in vitro, although the mechanism is not understood yet.

Medicinal Uses:
Research into fungal dressings for the treatment of ulcers, and bed sores, using fungal mycelial filaments, is on going. In the past, slices of A. campestris were applied to scalds, and burns in parts of Scotland.

Disclaimer:
The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplements, it is always advisable to consult with your own health care provider.

Taxonomy
This species was originally noted and named in 1753 by Carolus Linnaeus as Agaricus campestris. It was placed in the genus Psalliota by Lucien Quelet in 1872. Some variants have been isolated over the years, a few of which now have species status, for example, Agaricus bernardii Quel. (1878), Agaricus bisporus (J.E. Lange) Imbach (1946), Agaricus bitorquis (Quel.) Sacc. (1887), Agaricus cappellianus Hlavacek (1987), and Agaricus silvicola (Vittad.) Peck (1872).
Some were so similar they did not warrant even variant status, others have retained it eg. Agaricus campestris var. equestris (F.H. Moller) Pilat (1951) is still valid, and presumably favors pasture where horses have been kept. Agaricus campestris var isabellinus (F.H. Moller) Pilat (1951), and Agaricus campestris var.radicatus, are possibly still valid too. The specific epithet campestris is derived from the Latin campus.